EP3713700A1

EP3713700A1 - Tool for machining a workpiece

Info

Publication number: EP3713700A1
Application number: EP18808001.4A
Authority: EP
Inventors: Markus Kannwischer
Original assignee: Hartmetall Werkzeugfabrik Paul Horn GmbH
Current assignee: Hartmetall Werkzeugfabrik Paul Horn GmbH
Priority date: 2017-11-24
Filing date: 2018-11-23
Publication date: 2020-09-30
Also published as: CA3079631A1; JP7266033B2; WO2019101943A1; US11801562B2; DE102017127814A1; US20200254531A1; MX2020005185A; JP2021504159A; RU2739266C1; CN111479644A

Abstract

The invention relates to a tool (10) for machining a workpiece, comprising a cutting head (12) which has a sleeve (16) and a cutting element (18) fixed to the sleeve (16), and comprising a holder (14), to which the cutting head (12) can be detachably fixed. When the tool (10) is assembled, cutting head (12) and holder (14) are screwed to each other via an internal thread (40) arranged in the sleeve (16) and an external thread (42) corresponding thereto and arranged on the holder (14). In addition, when the tool (10) is assembled, cutting head (12) and holder (14) contact each other via a first axial contact surface (36) arranged on the sleeve (16), and a second axial contact surface (38) corresponding thereto and arranged on the holder (14), and a first conical contact surface (44) arranged on the sleeve (16) and a second conical contact surface (46) corresponding thereto and arranged on the holder (14).

Description

Tool for machining a workpiece

[0001] The present invention relates to a tool for machining a workpiece. The tool has a cutting head with a sleeve and a cutting body attached to the sleeve, on which at least one cutting edge is arranged. The cutting head extends along a first longitudinal axis. The tool further includes a holder to which the cutting head can be releasably secured. The holder extends along a second longitudinal axis.

Although the tool according to the invention is generally applicable to all types of

Relates to tools for machining a workpiece, the present invention relates in particular a milling tool, more preferably a Kugelbahnfrä- ser.

A generic tool is known from WO 2010/012367 A1. When milling pivot pin and hubs are usually special tools, so-called.

Ball track milling cutters, for use. These ball race cutters mill on the face side at different engagement widths and machining depths, for which purpose the ball race milling cutter is normally inclined at an angle, e.g. 20 °, is started. In some cases, the webs correspond to cylinder cut-outs, but in some cases the webs are also curved, which requires very rigid tools. Milling is carried out both in soft and in hardened materials. Depending on the application, different types of tools are currently used.

Exemplary ball race cutters are described in DE 199 56 592 A1 and DE 199 45 360 A1.

[0006] A particular challenge in the design of ball track cutters is to provide an interface between the holder and the cutting head, which has a corresponding rigidity in order to intercept the forces occurring during machining. The interface becomes due to the angled setting of the ball track milling cutters suspended between holder and cutting head in such tools a high bending stress. The interface must therefore be able to absorb this bending stress without having to accept losses in terms of the accuracy of the tool.

[0007] The international patent application WO 2010/012367 A1 already mentioned at the beginning shows a number of suitable cutting-edge solutions which satisfy the abovementioned requirements for ball track milling cutters. There is still room for improvement of this interface.

[0008] It is an object of the present invention to improve the above-described tool for machining a workpiece in such a way that the cut points between the holder and the cutting head are even more stable and allow an even more accurate positioning of the cutting head. This object is achieved on the basis of the aforementioned tool in that the sleeve has a first axial bearing surface which at least partially surrounds the first longitudinal axis and orthogonal to the first longitudinal axis, wherein the sleeve has a first conical contact surface, which first longitudinal axis at least partially surrounds and extends symmetrically to the first longitudinal axis, the sleeve further having an internal thread, which is disposed within the sleeve in a region which is located locally between the first axial bearing surface and the first conical contact surface, wherein the Holder has a second abutment surface which at least partially surrounds the second longitudinal axis and orthogonal to the second longitudinal axis, and wherein the holder has a second conical contact surface which at least partially surrounds the second longitudinal axis and is symmetrical to the second longitudinal axis, wherein the H Furthermore, it has an external thread, which is arranged on the holder in an area that is located locally between the second axial contact surface and the second conical contact surface, wherein, in the assembled state of the tool, the internal thread is screwed to the external thread , the first longitudinal axis coincides with the second longitudinal axis, the first axial abutment surface bears against the second axial abutment surface, and the first conical abutment surface bears against the second conical abutment surface.

Similar to a known from WO 2010/012367 A1 solution is the

Cutting head screwed onto the holder according to the present invention. New compared to the solution known from WO 2010/012367 A1, however, is the type of positioning of the cutting head relative to the holder. The positioning of the cutting head or the sleeve of the cutting head according to the invention via two corresponding conical surfaces and two corresponding planar surfaces.

The conical surfaces are present as the first and second conical contact surfaces

designated, wherein the first conical contact surface is arranged on the cutting head and the second conical contact surface is arranged on the holder.

The planar surfaces are referred to herein as first and second axial abutment surfaces, wherein the first axial abutment surface is arranged on the cutting head and the second axial abutment surface is arranged on the holder. The supporting contact surfaces, ie the conical and axial contact surfaces, are

each arranged on different sides of the inner or outer thread, so that the cutting head and the holder abut on the one side of the thread along the axial abutment surfaces and abut each other on the other side of the thread along the conical contact surfaces.

This type of interface provides for an extremely stable support and at the same time for a very accurate positioning. The axial contact surfaces only absorb forces in the axial direction. Conversely, the conical abutment surfaces simultaneously serve for better centering of the cutting head and absorb forces both in the axial and in the radial direction.

The use of conical contact surfaces in addition to the axial contact surfaces

brings significant benefits. Conical abutment surfaces have the advantage, in particular over cylindrical contact surfaces, of better centering of the cutting head, since manufacturing tolerances in the orthogonal direction to the longitudinal axis are reduced during the increasing screwing-in process. Furthermore, the conical surfaces can be brought together better in the direction of the longitudinal axis, since contact only occurs in the final positioning of the conical lateral surfaces. Therefore, the conical lateral surfaces wear much less than cylindrical lateral surfaces would do at this point. Another advantage lies in the larger area of the conical surface of the conical bearing surfaces in relation to a cylindrical surface of cylindrical bearing surfaces, which increases the bearing portion of the conical abutment surfaces.

Preferably, the cutting head and the holder in the assembled state of the tool contact exclusively along the inner or outer thread and along the axial and conical contact surfaces. Further contact surfaces or contact points do not exist according to this preferred embodiment.

According to a further preferred embodiment, the first axial abutment surface is arranged on an end face of the sleeve and the first conical abutment surface in the interior of the sleeve. The first conical bearing surface is thus well protected against damage. This is particularly advantageous for an exact positioning of the sleeve relative to the holder.

According to a further embodiment, a bevel is on a front side of the holder

arranged, which adjoins the second conical contact surface.

This embodiment has the advantage that the first conical contact surface during

Inserting the holder into the cutting head is not damaged. The chamfer arranged on the holder serves as an introduction chamfer.

According to a further embodiment, a radius is arranged on the holder between the external thread and the second axial abutment surface.

This radius serves as a transition radius between the external thread and the second axial abutment surface and in particular has the advantage that in this way the notch strength is increased.

According to a further embodiment, the holder has a shaft on which the

External thread is arranged, wherein the shaft is at least partially made of hard metal, and wherein the sleeve is at least partially made of steel.

The production of the holder shaft made of hard metal ensures high rigidity and

Stability of the shaft, which is of immense advantage especially in ball track milling. Compared to a holder made of steel, the shaft of the invention therefore has relatively long carburetor.

The holder further comprises a shaft holder, in which the shaft can be releasably secured, wherein the shaft holder is at least partially made of steel.

This results in the respective interfaces of the tool according to the invention in each case a transition from cemented carbide to steel or steel to hard metal, which in turn is for reasons of stability of advantage. The cutting body is preferably made of hard metal, cubic crystalline boron nitride (CBN) or polycrystalline diamond (PCD). The sleeve and the cutting body are preferably soldered together. In principle, however, other types of connections come into question, eg screwing.

According to a further embodiment, the first conical contact surface is inclined at a first angle of inclination relative to the first longitudinal axis. The second conical contact surface is inclined at a second inclination angle relative to the second longitudinal axis, wherein the first and the second inclination angle are equal.

The inclination angle thus correspond to half the opening angle of the respective cone.

The two angles of inclination are preferably in the range of 10 ° -45 °, more preferably in the range of 15 ° -30 °.

According to a further embodiment, the internal thread and the external thread

each designed as a trapezoidal thread.

Trapezoidal threads are very stable and are suitable for transmitting high forces.

Preferably, the internal thread and the external thread each have at least two

Threads on.

According to a further embodiment, a coolant channel extending along the second longitudinal axis is arranged in the holder. In the sleeve, a plurality of distribution channels are arranged, which wear into a cavity arranged in the sleeve, which corresponds in the mounted state of the tool with the coolant channel.

This allows the supply of coolant and lubricant directly or at least very close to the cutting area. The cavity in the sleeve serves to distribute the coolant and lubricant within the sleeve to the individual distribution channels. According to a further embodiment, a plane on a lateral surface of the sleeve

Surface arranged, which is aligned parallel to the first longitudinal axis.

This flat surface serves as an attack or clamping surface for a tool key for

Mounting the cutting head on the holder.

It is understood that the above and the still to follow

explanatory features are usable not only in the combination given, but also in other combinations or alone, without departing from the scope of the present invention.

The invention is described below with reference to the drawings

Embodiments explained in more detail. Show it:

Fig. 1 is a perspective view of an embodiment of the tool according to the invention;

FIG. 2 is an exploded view of the tool shown in FIG. 1; FIG.

Fig. 3 is a sectional view of the tool shown in Fig. 1;

4 shows a perspective view of a cutting head of the tool shown in FIG. 1;

Fig. 5 is an exploded view of the cutting head shown in Fig. 4;

Fig. 6 is a front plan view of the cutting head shown in Fig. 4;

Fig. 7 is a first sectional view of the cutting head shown in Fig. 6;

Fig. 8 is a second sectional view of the cutting head shown in Fig. 6; 9 is a perspective view of a cutting head according to a second embodiment; and

10 is a perspective view of a cutting head according to a third embodiment.

1-3 show a first embodiment of the tool according to the invention in the assembled state (Fig. 1), in a disassembled state (Fig. 2) and in a sectional view (Fig. 3). The tool is designated therein in its entirety by the reference numeral 10.

The tool 10 is designed as a ball raceway milling cutter. The tool 10 includes a

Cutting head 12 and a holder 14 in which the cutting head 12 is releasably attached. The cutting head 12 has a sleeve 16 and a cutting body 18 fastened to the sleeve 16.

The holder 14 comprises a shaft 20 and a shaft holder 22, in which the shaft

20 is releasably attached. The shaft holder 22 has at its rear end a tool interface 24 by means of which the tool 10 can be clamped in a machine tool (not shown).

The sleeve 16 of the cutting head 12 is bolted to the shaft 20 of the holder 14. The

Shank 20 is secured against rotation in the shaft holder 22. Preferably, the shaft 20 is shrunk into the shaft holder 22. In principle, however, a screw connection or another type of non-rotatable connection would be conceivable at this point.

The cutting head 12 extends substantially along a first longitudinal axis 28.

The holder 14 extends substantially along a second longitudinal axis 30. Both longitudinal axes 28, 30 coincide in the assembled state of the tool 10. The individual components of the tool 10 are preferably produced in an alternating sequence of hard metal and steel. The cutting body 18 is preferably made of hard metal. The sleeve 16 is preferably made of steel. The shaft 20 is preferably made of hard metal. The shaft holder 22 is preferably made of steel.

The sleeve 16 and the cutting body 18 are soldered together. Preferably, the

Cutting body 18 by means of a brazing blunt soldered to the sleeve 16. A bore 32 arranged centrally in the cutting body 18 (see FIG. 7) and a pin 34 corresponding thereto, which is arranged on the sleeve 16, serve to support the positioning during the soldering process. It should be noted, however, that other types of connection between the sleeve 16 and the cutting body 18, for example a screw connection, are possible.

The present invention relates in particular to the connection between the cutting head 12 and holder 14, more particularly the connection between the sleeve 16 and the shaft 20. At this interface, an extremely stable, rigid and very accurately positioned connection is achieved in the following manner: The Sleeve 16 has a first axial abutment surface 36, which corresponds to a shaft 20 disposed on the second axial abutment surface 38. In addition, the sleeve 16 has an internal thread 40 which corresponds with a corresponding external thread 42 which is arranged on the shaft 20. Furthermore, the sleeve 16 has a first conical contact surface 44 which corresponds to a second conical contact surface 46 arranged on the shaft 20.

Preferably, cutting head 12 and sleeve 20 occur in the assembled state of the tool

10 only along the internal or external thread 40, 42 and along the axial and conical contact surfaces 36, 38 and 44, 46 with each other. Circumferentially acting forces are absorbed via the internal thread 40 and the external thread 42. Axial forces are absorbed both via the conical contact surfaces 44, 46 and via the axial contact surfaces 36, 38. The conical contact surfaces 44, 46 also absorb forces in the radial direction due to their inclination. The conical bearing surfaces 44, 46 serve in addition to the stable support and a precise positioning of the cutting head 12 relative to the shaft 20. The first axial abutment surface 36 is disposed on the lower end side of the sleeve 16 and extends orthogonal to the first longitudinal axis 28 of the cutting head 12. The first axial abutment surface 36 is preferably designed as an annular surface.

The second axial abutment surface 38 is arranged on the upper side of the shaft 20 and extends orthogonal to the second longitudinal axis 30 of the holder 14. The second axial abutment surface 38 is preferably also designed as an annular surface.

The first conical contact surface 44 is disposed inside the sleeve 16 and extends transversely, that is not parallel, to the first longitudinal axis 28 of the cutting head 12. The first conical contact surface 44 is preferably at a first angle of inclination oti relative to the first longitudinal axis 28th inclined (see Fig. 7). This inclination angle oti corresponds to half the opening angle of the cone, on the lateral surface of which the first conical bearing surface 44 lies. The first inclination angle oti is preferably in the range of 10 ° -45 °, more preferably in the range of 15 ° -30 °. The first conical contact surface 44 preferably completely surrounds the first longitudinal axis 28.

The second conical abutment surface 46 is arranged on the upper end side of the shaft 20 and inclined at a second inclination angle a ₂ , which is the same as the first inclination angle ai, relative to the second longitudinal axis 30 of the holder 14. The internal thread 40 provided in the interior of the sleeve 16 is arranged in a region which is located locally between the first axial abutment surface 36 and the first conical abutment surface 44. Similarly, the external thread 42 arranged on the shank 20 is arranged in a region which is located locally between the second axial abutment surface 38 and the second conical abutment surface 46.

The fact that the internal thread 40 in a region between the first axial

Bearing surface 36 and the first conical bearing surface 44 is arranged, but does not imply that the internal thread 40 at its two ends directly adjacent to the first axial abutment surface 36 and the first conical abutment surface 44. This may or may not be the case. In between, an undercut or a pure distance can also be provided in each case. Likewise, the second axial abutment surface 38 and the second conical abutment surface 46 may abut directly on the two opposite ends of the male thread 42, but need not. In between, an undercut or a pure distance can also be provided in each case.

The internal thread 40 and the external thread 42 are preferably designed as a trapezoidal thread, each having at least two threads.

Above the second conical abutment surface 46, a bevel 48 is arranged on the shank 20, which is intended to prevent damage to the first conical abutment surface 44 when the shank 20 is inserted into the sheath 16. The second conical contact surface 46 is thus arranged between this chamfer 48 and the external thread 42. At the lower end of the external thread 42, ie between the external thread 42 and the second axial abutment surface 38, a transition radius 50 is arranged (see FIG. 2). This transition radius 50 serves to improve notch strength.

As can further be seen from FIG. 8, the internal thread 40 does not directly adjoin the first conical contact surface 44. Between the internal thread 40 and the first conical contact surface 44, an internal free recess 52 is arranged. At the opposite end of the internal thread 40, an internal free groove 54 is also arranged.

The tool 10 according to the invention further comprises a coolant channel 56, which runs in the interior of the holder 14. The coolant channel 56 extends inter alia in the interior of the shaft 20 along the longitudinal axis 30. At the top of the shaft 20, the coolant channel 56 opens into a cavity 58 in the interior of the sleeve 16. From this cavity 58, the coolant and lubricant spreads out a plurality of distribution channels 60, which are located inside the sleeve 16 and exit at the top of the sleeve 16.

On the outside of the sleeve 16, a flat surface 62 is further provided, which as

Attack surface for a fork wrench for mounting the cutting head 12 is used. These plane surface 62 preferably runs parallel to the first longitudinal axis 28 of the

Cutting head 12.

FIGS. 9 and 10 show further possible embodiments of cutting heads 12 ', 12 ".

They differ from the cutting head 12 according to the first embodiment substantially in the geometry of the cutting. For example, the cutting bodies 18 'shown in FIG. 9 are plate-shaped cutting bodies made of CBN, which are individually soldered onto the sleeve 16'. The cutting body 18 "shown in Fig. 10 is suitable, for example, for a cutter for grooving.

The internal structure as well as the inventive interface between sleeve 16 and shaft

However, in the exemplary embodiments shown in FIGS. 9 and 10, there is no difference, or only insignificant, for the invention from the first exemplary embodiment shown in FIGS. 1-8, for which reason statements relating to this are not repeated at this point.

Claims

claims

A tool (10) for machining a workpiece, comprising: a cutting head (12) having a sleeve (16) and a cutter body (18) attached to the sleeve (16) on which at least one cutting edge (26) is disposed where the cutting head (12) extends along a first longitudinal axis (28); and a retainer (14) to which the cutting head (12) is releasably securable, the retainer (14) extending along a second longitudinal axis (30); wherein the sleeve (16) has a first axial abutment surface (36) at least partially surrounding the first longitudinal axis (28) and orthogonal to the first longitudinal axis (28), the sleeve (16) having a first conical abutment surface (44 ) which at least partially surrounds the first longitudinal axis (28) and extends symmetrically to the first longitudinal axis (28), and wherein between the first axial abutment surface (36) and the first conical abutment surface (44) extends along the the first longitudinal axis (28) extending portion within the sleeve (16) is provided, in which an internal thread (40) is arranged, wherein the holder (14) has a second axial abutment surface (38) which the second longitudinal axis (30) at least partially surrounds and orthogonal to the second longitudinal axis (30), wherein the holder (14) has a second conical bearing surface (46) which at least partially surrounds the second longitudinal axis (30) and symmetrical to the second longitudinal axis and between the second axial abutment surface (38) and the second conical abutment surface (46) a region extending along the second longitudinal axis (30) is provided on the holder (14), in which an external thread (42 ), wherein, in the mounted state of the tool (10), the internal thread (40) is screwed to the external thread (42), the first longitudinal axis (28) coincides with the second longitudinal axis (30), the first axial abutment surface (36) abuts the second axial abutment surface (38) and the first conical abutment surface (44) abuts the second conical abutment surface (46).

2. Tool according to claim 1, wherein the first axial abutment surface (36) on an end face of the sleeve (16) is arranged, and wherein the first conical abutment surface (44) in the interior of the sleeve (16) is arranged.

3. Tool according to claim 2, wherein in the interior of the sleeve (16) between the first conical contact surface (44) and the internal thread (40), an internal recess (52) is arranged.

4. Tool according to one of claims 1-3, wherein on a front side of the holder (14) has a chamfer (48) is arranged, which adjoins the second conical contact surface (46).

5. Tool according to one of claims 1-4, wherein on the holder (14) between the external thread (42) and the second axial bearing surface (38), a radius (50) is arranged.

6. Tool according to one of claims 1-5, wherein the holder (14) has a shaft (20) on which the external thread (42) is arranged, wherein the shaft (20) is at least partially made of hard metal, and wherein the sleeve (16) is at least partially made of steel.

7. Tool according to one of claims 1-6, wherein the holder (14) has a shaft holder (22) in which the shaft (20) is releasably attachable, wherein the shaft holder (22) is at least partially made of steel ,

8. Tool according to one of claims 1-7, wherein the sleeve (16) and the

Cutting body (18) are soldered together.

The tool of any one of claims 1-8, wherein the first conical abutment surface (44) is inclined at a first inclination angle (ai) relative to the first longitudinal axis (28), and wherein the second conical abutment surface (46) is under a second Inclination angle (a ₂ ) is inclined relative to the second longitudinal axis (30), wherein the first and the second inclination angle are equal.

10. Tool according to claim 9, wherein for the first and the second tilt angle applies: 10 ° <CH = a ₂ ^ 45 °.

1 1. A tool according to any one of claims 1-10, wherein the internal thread (40) and the external thread (42) are designed as a trapezoidal thread.

12. Tool according to one of claims 1-1 1, wherein the internal thread (40) and the external thread (42) each have at least two threads.

13. Tool according to one of claims 1-12, wherein in the holder (14) along the second longitudinal axis (30) extending coolant channel (56) is arranged, and wherein in the sleeve (16) a plurality of distribution channels (60) are arranged, which in a in the sleeve (16) arranged cavity (58) tired, which corresponds in the assembled state of the tool (10) with the coolant channel (56).

14. Tool according to one of claims 1-13, wherein on a lateral surface of the sleeve (16) a planar surface (62) is arranged, which is aligned parallel to the first longitudinal axis (28).

15. Tool according to one of claims 1 -14, wherein the tool (10) is a milling tool.